Staurois tuberilinguis facts for kids
Quick facts for kids Staurois tuberilinguis |
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| Adult seen along stream in Mt. Kinablu National Park | |
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Rana tuberilinguis (Boulenger, 1918) |
The Staurois tuberilinguis is a type of frog often called the Borneo splash frog or green-spotted rock frog. It belongs to the true frog family, known as Ranidae. This frog is active during the day (diurnal) and at dawn/dusk (crepuscular). It's very similar to another frog, Staurois parvus (the Borneo rock frog). In fact, many scientists think they might be the same species!
You can usually find these frogs in the tropical rainforests of Borneo, Malaysia. They love living near fast-flowing rivers and streams. Because their homes are often noisy, these frogs have special ways to talk to each other. They use both sounds and visual signals. Even though S. parvus seems to be decreasing in some areas, it's currently listed as "least concern" by the IUCN Red List of Threatened Species. However, its habitat is shrinking due to things like cutting down forests and dirtying streams.
Contents
About the Borneo Splash Frog
What Do Tadpoles Look Like?
Young S. parvus tadpoles have flat bodies and tiny eyes hidden under their skin. They look a bit like worms with long tails and small fins. Their skin is almost clear. It's very hard to tell them apart from S. tuberilinguis tadpoles. The main difference is that S. parvus tadpoles have small white spots on their bodies and tails, which S. tuberilinguis tadpoles do not.
What Do Adult Frogs Look Like?
Adult male S. parvus frogs are about 27 to 31 millimeters (1.1 to 1.2 inches) long from their snout to their bottom. Females are a bit bigger, measuring 33 to 38 millimeters (1.3 to 1.5 inches). They have a thin head with a pointy snout. One of their fingers, the fourth one, is quite short, which helps tell them apart from other frogs.
These frogs don't have teeth on their vomer bone (a bone in the roof of their mouth). They also have a special bump on their tongue. Their eggs are clear. What's really cool is that the bottom of their toes has tiny structures called nanopillars. These act like a temporary glue, helping the frog stick firmly to rocks even in fast-moving water!
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Close Frog Relatives
S. parvus is most closely related to S. tuberilinguis. They look so much alike that it's hard to tell them apart, except for one or two small differences. Even genetic tests show they have very similar DNA. This is why scientists often debate if they are truly different species. Other close relatives include Staurois guttatus and the Staurois latopalmatus.
Where They Live
You can find these frogs in northern Borneo, including Sabah and Sarawak in Malaysia, Brunei, and northeastern Kalimantan in Indonesia. They live at elevations up to 2,000 meters (about 6,560 feet) above sea level.
A smaller frog, S. parvus, was first found only in the Crocker Range in Sabah, Malaysia. For a while, scientists thought it was the same as S. tuberilinguis. But more recent studies, looking at their body shapes and DNA, have confirmed that S. parvus is indeed a separate species.
These frogs prefer to live along the edges of small, rocky streams with clear water in untouched rainforests. You can often spot them sitting on rocks or plants near the water, especially where the water flows quickly. They lay their eggs in streams, and the males make calls during the day. Like other Staurois frogs, they use visual signals to find mates.
Life Cycle and Growth
When S. parvus tadpoles change into young frogs (a process called metamorphosis), their feet have white and bluish colors. These colors help them with visual signaling. As they grow from young frogs to adults, these colors become brighter, making their signals even clearer. Studies show that this color change happens as the frogs become sexually mature. Young S. parvus frogs start out bright green. This helps them blend in with the mossy rocks near rivers and streams in the rainforest.
Frog Behavior
Mating Rituals
About one to two years after they are born, S. parvus frogs become adults and are ready to mate. Males will make a mating call. Then, they settle near the riverbanks and wait for females to arrive. During this time, there are many more males than females by the river. This leads to a lot of competition between males. Males puff out their vocal sacs and change their body position to show off their size and colors. This helps them scare away other males trying to claim their territory. The larger males usually take over the shallow parts of the river or areas with thick plants, which are better for laying eggs.
Once females arrive, the males make a special call to let the females know they are there. After a female notices a male, he will show off his physical strength and health using visual signals. This usually involves "foot flagging" or "foot flashing." Foot flagging is when a frog lifts a back leg away from its body to show off the webbing on its foot to other frogs. Older male S. parvus frogs have brighter body colors, so the color helps females judge a male's age and development. Also, because foot flagging and flashing take a lot of energy, a more complex display shows how strong the male is.
S. parvus females lay their eggs in fast-flowing water. To keep the eggs safe from being washed away, the female chooses a spot under thick leaves, between rocks, or in calmer pools on the side of the stream.
How They Communicate
S. parvus frogs live in noisy tropical rainforests near fast-moving streams. This makes it hard to communicate using only sounds. So, S. parvus has many ways to talk effectively even with a lot of background noise.
One way they do this is by making their calls louder. If the background noise is too loud, the Borneo rock frog can increase the volume of its calls by up to 8 decibels so that other frogs can hear them. They can also slightly change the pitch of their calls away from their usual frequency of 5578 Hz. Scientists think they do this to avoid their calls getting mixed up with those of other frogs. Also, S. parvus has a unique call that helps it stand out from similar frogs like S. guttatus. Depending on how many frogs are listening and how loud it is, S. parvus might make more notes or longer calls. This probably gives the other frog more chances to recognize the call.
In very loud places where sound communication isn't possible, the Borneo rock frog uses visual signals. S. parvus has many visual displays, most commonly foot flagging and foot flashing. Less common visual signals include arm waving, standing tall, crouching, and opening their mouth.
- Foot flagging is when the frog lifts one of its back legs and swings it outwards and backwards in an arc. This usually lasts about 1.5 seconds. During this time, the frog spreads its webbed toes, making its bright white webbing clearly visible.
- Foot flashing is similar but faster. The frog stretches its back leg out and pulls it back immediately. These flashes are very quick, lasting about 0.83 seconds, and usually happen right after a sound call.
In noisy rainforests, the sound call helps get the attention of another frog. Once the S. parvus has the other frog's attention, it follows up with a visual display, usually a foot flag or flash. The less common visual displays (standing tall, crouching, and arm waving) are usually used by males when they are close to other males. These displays typically show how strong the male is.
Overall, S. parvus has a special system of communication that uses both sound and sight. This helps them adapt and communicate in changing and noisy environments. For example, when it rains heavily and the background noise gets louder, or when there isn't much light, visual communication becomes more important. But if it's quiet and there's enough light, sound communication works better. This adaptive system helps S. parvus deal with the changing conditions in their rainforest home.
How Their Bodies Help Them Communicate
S. parvus frogs need very precise and fast muscle control to perform visual signals like foot flagging and flashing. Special hormones, like testosterone, help control these complex movements. Studies have shown that the body systems responsible for these visual displays in frogs and birds need these hormones to work correctly. If these hormones are blocked, the visual signals in S. parvus stop working, but their vocal communication is not affected. This shows how important these hormones are for their visual communication.
What They Eat
When S. parvus are tadpoles, they only eat decomposed plants and algae. Once they change into adult frogs, their diet expands to include insects. However, because adult S. parvus are small, they mostly eat small insects like flies, moths, and dragonflies. Generally, S. parvus are "opportunistic feeders." This means they will eat almost anything that comes within their reach. So, their adult diet mostly depends on which prey insects are most common during different seasons of the year.
Saving the Frogs
The biggest threats to S. parvus populations are deforestation (cutting down forests) and the resulting pollution and changes to stream conditions. Even though S. parvus is currently listed as a species of "Least Concern" on the IUCN Red List, its numbers have been going down steadily in recent years. This is due to more habitat loss and pollution. These frogs live in protected areas like Mt. Kinabalu and Gunung Mulu National Parks. However, the mountains in Kalimantan need more urgent protection to help these frogs survive.
